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I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

10 September 2011

B12 & Human Evolution

The latest dose of Vegan Outreach contains an interesting question:
After I mentioned that vegans must rely on fortified foods or supplements for vitamin B12, this person cited that fact as evidence that nature intends for humans to consume animals or animal secretions. This person's point had me incapable of responding. What is your take on this comment?
I get this a question a lot, too, and there are a couple of ways to handle it. One is the way Jack Norris responded with, an entirely appropriate pointing-out that nature does not "intend" anything. In most cases, that suffices.

Problem is, it sometimes comes off as slightly dismissive, if not evasive. So, I have come up with another, equally valid response.

"B12 deficiency is a common problem even for meat-eaters. The Framingham Study determined that up to 40 percent of Americans have 'sub-optimal' B12 blood levels... and vegans are not 40 percent of America. So, it's a common dilemma, but fortunately, nature has engineered a way around it: the technical term is enterohepatic circulation. It's a mouthful, but all it really means is that once you have sufficient B12 stores, your body continuously recycles it through the bile system, keeping you at functional levels for years, sometimes decades. We should not rely on this by any means, but it's a fallacy to argue that because we need supplements or fortified foods to get B12, nature therefore 'intends' us to eat meat. Nature also engineered us to survive a long time without any external B12 sources. So the issue really comes down to ethics and free will, not the laws of nature."

I've tested versions of this response out on some evo-savvy interlocutors, and it works almost every time. For those who want evidence, I point out that the process is present in monkeys, indicating that enterohepatic circulation of cobalamin has likely been ancestral to our lineage since before the appearance of the Miocene "apes" about 22 Ma.

Having said that, though, I'm neither a doctor nor a dietitian, so turn to Jack Norris and Ginny Messina for any health-related questions.


  1. My diet is foremost an ethical choice, so the B12 issue is not so important to me. However, because enterohepatic circulation isn’t enough to maintain optimal B12 levels for 40% of a mixed-diet population anyway, it would not seem a big selling point in dietary choices.

    I do find Jack’s answer adequate. Every American who eats processed foods, salt, milk, breakfast cereals, or bread is consuming a fortified diet without much awareness. If they take vitamins (a huge industry), they are obviously supplementing their diet. Logically speaking, why would vegans be criticized for the same behavior?

    While research demonstrates that a vegan diet is optimal in meeting recommendations for many nutrients and avoiding unhealthy levels for others, I take a B12 supplement.

    As a member of a still wealthy nation with abundant resources, I am grateful I can pick, choose, and supplement my diet to begin with.

  2. There is a contradiction between your answer and what Dr. Michael Greger says in one of his videos on NutritionFacts.org here:

    He says, sarcastically: "One thing I hear from whining vegans is that B12 deficiency isn't exclusive to vegetarians. Meat-eaters get it too." He quotes a British study which found that 99% of meat-eaters get sufficient B12 but only 27% of vegans do. He then goes on to urge vegans to take their supplements. When 99% of omnivores are getting sufficient B12, I don't think it is correct to say, as in your answer, that "B12 deficiency is a common problem even for meat-eaters."

    Until someone can satisfactorily reconcile the Framingham study and the British study quoted by Dr. Greger, I am not sure what is the best answer to the B12 question.

  3. Here's a very helpful quote from "Vegan for Life", (it appears right beneath a quote by you, Rob!):

    "And Tom Billings, who writes the Beyond Veg website, says, "Further, if the motivation for your diet is moral and/or spiritual, then you will want the basis of your diet to be honest as well as compassionate. In that case, ditching the false myths of naturalness presents no problems; indeed ditching the false myths means that you are ditching a burden."

    We agree that it just doesn't matter whether a vegan diet is our historical way of eating or not. The fact is, it makes sense now to choose a vegan diet. And whose diet is really natural, anyway? The assumption that there is one natural prehistoric diet, which can be approximated today and would be optimal for modern humans, is dubious at best.
    Today's commercial plant foods and meats are different from the foods available in prehistoric times. We eat hybrids of plants and we feed foods to animals that they would not normally eat. Additionally, the U.S. food supply is routinely fortified with a host of vitamins and minerals. Even those who strive to eat a more "natural" diet as adults have normally benefited from fortified foods as children. It is quite unlikely that anyone is eating a natural diet in today's world.
    Taking a vitamin B12 supplement is a small thing that can make all the difference in your health as a vegan. Based on our current knowledge of vitamin B12 requirements and sources, supplementation is not a subject for debate. Vitamin B12 supplements or fortified foods are an essential part of a well-balanced and responsible vegan diet at all stages of the life cycle."

    Another quote from later on in the book:

    "There is evidence to suggest that some signs of aging - such as loss of hearing, forgetfullness, confusion, and depression - could be related at least in part to inadequate vitamin B12 since this vitamin affects the nervous system. A marginal intake of vitamin B12 can also raise the risk for stroke, a problem in older people.
    This is where vegans might have the edge, as we discussed in Chapter 3. Absorption of vitamin B12 from meat, dairy, and eggs declines among a large percentage of older people because of digestive changes. Changes causing decreased absorption may affect as many as 30 percent of people over the age of fifty and 37 percent of those over the age of eighty. However, most of these changes don't affect the absorption of vitamin B12 from supplements and fortified foods, so health professionals advise all people over the age of 50 to get at least half of their B12 from these sources. Many people, though, aren't aware of this recommendation. That's where the vegan advantage comes in, because vegans who are educated about good nutrition are already taking B12 supplements."

    (From tips for older vegans:)
    "- Take a vitamin D supplement. It's unlikely that older people - vegan or omnivore - can meet needs otherwise."

    Rejecting taking supplements can have a detrimental effect on your health, and if you really wanted to be consistent in rejecting any foods that can be deemed to be unnatural, you would have to reject a whole lot more than vitamin B12 supplements, as pointed out by Ginny Messina and Jack norris in "Vegan for Life".

  4. The way I handle this question is similar to how Norris does, but taking it a step further--even if you can prove that nature intended a diet that doesn't involve supplementing or fortifying--what's it matter if, theoretically or actually, a diet filled with 'unnatural' things is conclusively proven to be healthier and better for you?

    For example, what if scientists in a lab create a new substance not found in nature at all that has indisputable health benefits that no one in their right mind could argue against taking. Nature didn't intend that substance to exist, but so what?

  5. The study quoted by Dr. Michael Greger - and indeed, much of his work is highly questionable for a number of reasons. B12 is of crucial importance - he's spot on with that, but the incidence of B12 deficiency is based on testing methods that have been proven incredibly inaccurate. The selection process for the study is also biased.

    A vegan should have 10ug (micrograms) of B12 every day from a supplement dissolved in the mouth (as it is absorbed much more readily through the cheek lining than the stomach lining). The Vegan Society have a good piece on nutrition written here: http://www.vegansociety.com/lifestyle/nutrition/b12.aspx And its facts are endorsed by more than just one general doctor!

  6. I'm surprised no one has mentioned yet what I learned in Becoming Vegan, written by a Registered Dietitian. B-12 is created by bacteria found in soil. When cows and other animals eat dirt with the plants they eat, they also ingest the bacteria that create B-12. B-12 is stored in their tissues and when we eat their tissues we also eat the B-12. Humans don't eat dirt with their plants anymore because we are obsessed with cleanliness so we also no longer ingest any B-12 from soil. So B-12 is from a bacteria found in the soil, not from an animal or a plant. Also wanted to say I really like your blog and find it very interesting!

  7. I agree with Fiona: you didn't know about that whole b12 is from dirt thing?

    Also RE: dietary B12 vs B12 deficiency; there is a simple, but perhaps not obvious reason for this disconnect: most people get plenty of B12 in their diet (especially meat eaters) however, most deficiency is due to a (genetic) problem with absorbing the B12 that you actually do consume: thus you can be deficient while consuming adequate B12

  8. Anne Osborne (and her children), Matthew Grace (and his daughter) are just a couple amongst the famous representing an entire world-wide spread community of decades-long or born followers of a fruitarian or frugivore diet. No supplements (that includes B12). No signs of deficiencies...on the contrary (ex. Matthew Graze prior to his change in diet was on a wheelchair waiting for the coffin to be ready...diagnosed with MS).

    You may argue, of course, these are just anecdotal cases but we are getting more and more (to know) which would suggest that any B12 "deficiency" symptoms may not be caused by lack of animal anything in the diet.

    Whatever theory we want to come up with, we need to take into account this.

    Also, we seem to be willing to ignore the fact that no animal eat accordingly to what they think but accordingly to what they feel (availability allowing). We are the only animal that need to go to a lab in order to decide what is better for our body. It sounds absurd to me. One day one scientist (or an entire community indeed) will find something good about shit and decided to build a theory based on that and convince everybody that shit is good for them in spite of the fact that shit is repugnant to all of us...and so is meat. I've never found a child, prior to social conditioning, who likes raw meat; not a single one. Never found one who instinctively like to kill...all the contrary; they need to be socially forced or "convinced". No animals is forced to eat (or kill) this or that in nature. They have it, if, instinctively. At "best" they are shown by parents how to do it but not forced. The instinct must be there (biochemical changes, pleasure etc.) and can only be awaken. We do not have any instict to do so. Just speak with people working in slaughterhouses and even farmers. None likes killing...it's always because they feel they have to for some reason or another.

    Take care,

  9. Gio, you've clearly never seen my 3-yr old stomping on ants. Which we HATE to see her do.